Search for dissertations about: "chain elongation"

Showing result 1 - 5 of 40 swedish dissertations containing the words chain elongation.

  1. 1. On the way of making plants smell like moths - a synthetic biology approach

    University dissertation from Lund University, Faculty of Science, Department of Biology

    Author : Bao-Jian Ding; Lunds universitet.; Lund University.; [2014]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; moth pheromone; transcriptome; fatty acyl desaturase; fatty acyl reductase; acetyltransferase; chain shortening; chain elongation; heterologous expression; synthetic biology; plant expression;

    Abstract : Popular Abstract in Chinese 在世界許多地方蛾類幼蟲是主要的農業害蟲,但也有蛾類養殖業為獲取其絲綢蠶繭,例如家蠶。其實它也是第一個也是最好的研究揮發性有機分子用於傳遞信息的昆蟲研究模型。一般來說是雌蛾釋放信息素通過很長的距離來吸引雄性同類,而且具有出色的靈敏度和特異性。至今有記載的蛾類信息素都屬於同一類化合物(脂肪酸衍生物), 在信息素腺體內合成。信息素的生物合成涉及到脂肪酸的脫飽合,碳鏈縮短,並最終還原,乙酰化或氧化成醛等。這些反應過程中的酶已經進化到具有專一性,專門用於生產複雜的化學信號,使得蛾類的信息素存在豐富的化學多樣性。在本論文中,首先對幾個脫飽和酶進行研究。第一篇文章對冬尺蠖的脫飽合酶進行克隆並在酵母中通過異源表達證明了它具有把順十一,順十四,順十七-二十碳三烯酸轉化成順十一,順十四,順十七,十九-二十碳四烯酸的能力。這是有史以來第一個對甲基端脫飽合酶的報導。第二篇文章報導了來自蘋果蠹蛾和梨小食心蟲的脫飽合酶。它們都使用不飽和的十二碳烯醇和乙酸酯作為性信息素成分。在蘋果蠹蛾中發現兩個脫飽和酶連續工作產生共軛雙鍵。但在梨小食心蟲中,發現是由同一個脫飽和酶工作兩次產生的共軛雙鍵。這項研究提供了在蛾信息系素腺體內可以生產共軛二烯的又一個例子。第三篇文章對十一位脫飽和酶的立體特異性進行了調查。薔薇斜條捲葉蛾的十一位脫飽和酶作用於飽和十四酸,產生的順十一十四酸比反十一十四酸等於一百比四十七的混合物; 而來自於斑點捲葉蛾的脫飽和酶也作用於十四個碳飽和酸,但只生產純的反十一十四酸。通過對這兩個脫飽和酶的定點突變研究證明,一個在蛋白的羧基末端的氨基酸對脫飽和酶的順式活性至關重要。第四篇文章的研究集中在脂肪醇乙酰轉移酶,其在許多蛾類性信息素的生物合成途徑中承擔很大的作用。它催化的反應是轉移乙酰基給脂肪醇形成乙酸酯。由於此酶沒有在昆蟲中被克隆到,本研究異源表達了植物來源的乙酰基轉移酶,在酵母系統中測試其轉化蛾類性信息素脂肪醇的功能。結果表明其可以轉化碳鍊長度範圍從十個碳到十八個碳,不同雙鍵位置的各種脂肪醇,成為其相應的乙酸酯。第五篇文章利用下一代測序技術對黃地老虎信息素腺體進行分析,鑑定出許多與信息素合成相關的基因及過程,例如脂肪酸合成酶、脫飽合酶、貝塔氧化、還原酶、乙酰基轉移酶等等。在第六篇文章中利用煙草作為生物反應器來生產蛾類信息素來證明這個理論是可行的。通過瞬時表達四個蛾類信息素合成基因本研究成功生產出典型的蛾類信息素並證明了其具有能吸引雄蛾的生物活性。雖然利用植物生產的信息素的成份和比例沒有經過優化,但還是誘捕到大量的稠李巢蛾和蘋果巢蛾,其效果與有機合成的信息素相匹配。我們的長期目標是利用轉基因植物來生產任何類型的蛾類信息素。這種新穎的利用合成生物學的技術來製備信息素的方法將來也許會成為害蟲綜合防治的首選。 Popular Abstract in Swedish Nattfjärilslarver är viktiga jordbruksskadedjur i många delar av världen. Men det finns nattfjärilarar som odlas för deras silkeskokong, till exempel den anmärkningsvärda silkesfjärilen, Bombyx mori. READ MORE

  2. 2. Enzymes involved in heparan sulfate chain elongation : Function of a novel family of tumor suppressors?

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Thomas Lind; Uppsala universitet.; [1999]
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Biochemistry; heparan sulfate; biosynthesis; glycosyltransferase; EXT1; EXT2; UDP-glucosedehydrogenase; KfiC; Biokemi; MEDICINE Chemistry Biochemistry; MEDICIN Kemi Biokemi; Medical and Physiological Chemistry; medicinsk och fysiologisk kemi;

    Abstract : Heparan sulfate (HS) is a glycosaminoglycan associated with many physiological functions such as regulation of growth factor action and cell adhesion. The HS polysaccharide is synthesized by alternating addition of D-glucuronic acid (GlcA) and N-acetyl-D-glucosamine (GlcNAc) units from the corresponding UDP-sugar precursors. READ MORE

  3. 3. Metabolic Significance of Fatty Acid Elongation

    University dissertation from Stockholm : Department of Physiology, Stockholm University

    Author : Damir Zadravec; Stockholms universitet.; [2010]
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICINE Physiology and pharmacology Physiology; MEDICIN Fysiologi och farmakologi Fysiologi; fysiologi; Physiology;

    Abstract : Very long-chain fatty acids (VLCFAs), including polyunsaturated fatty acids (PUFAs), are essential lipids whose functional diversity is made possible by variation in their chain length and degree of unsaturation. Fatty acids can either be derived directly from the diet or they can be synthesized de novo through lipogenesis, up to 16 carbons in length by fatty acid synthase. READ MORE

  4. 4. Characterizing Elongation of Protein Synthesis and Fusidic Acid Resistance in Bacteria

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Srihari Nagendra Ravi Kiran Koripella; Uppsala universitet.; [2013]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ribosome; Elongation factor-G; FusB; GTP; Staphylococcus aureus; Escherichia coli and Fusidic acid; Molecular Biology; Molekylärbiologi;

    Abstract : Protein synthesis is a highly complex process executed by the ribosome in coordination with mRNA, tRNAs and translational protein factors. Several antibiotics are known to inhibit bacterial protein synthesis by either targeting the ribosome or the proteins factors involved in translation. READ MORE

  5. 5. Elovl3 and very long chain fatty acids; role in metabolism

    University dissertation from Stockholm : Wenner-Grens institut för experimentell biologi

    Author : Andreas Jakobsson; Stockholms universitet.; [2005]
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Fatty acids metabolism elongation; MEDICINE Physiology and pharmacology Physiology; MEDICIN Fysiologi och farmakologi Fysiologi;

    Abstract : Fatty acids (FA) are important in several aspects of cellular function, for example as structural molecules and metabolic substrates. The bulk of FA up to 16 carbons (palmitic acid) in length are synthesised by a cytosolic enzyme complex called fatty acid synthase (FAS), while FA can be further elongated into very long-chain fatty acids (VLCFA) by membrane-bound enzymes in the endoplasmatic reticulum (ER). READ MORE